The present invention relates to a data transmission system and more particularly to a data transmission system suitable for use, for example, in transmitting pricing data to electronic shelf labels in retail stores, such as supermarkets, and for displaying the data. Of course it will be appreciated that the invention may be used in any situation wherein data is transmitted to many different locations remote from a central base station and has particular utility where the data is frequently changing. For example the invention could be used in building paging systems or in warehousing, for inventory control.
A number of electrical or electronic systems have been proposed in the past for providing warehouse and supermarket shelf labels. Such systems of course considerably reduce or eliminate the labour costs associated with maintaining and up-dating shelf labels and because of their expediency, reduce financial loss due to price change lags. Thus the known electrical or electronic systems provide considerable advantage but unfortunately they also introduce some technical problems. For example, any system which requires direct wiring is expensive to install and considerably reduces the flexibility of moving and re-arranging shelves which is a common practice in supermarkets.
Another system which has been proposed uses radio broadcasts to send radio frequency (r.f.) signals to up-date information of electronic shelf labels (modules). This sytem overcomes the problem of connecting wires but requires a battery to power each module and an antenna at each module to transmit and receive the r.f. signal. Both these requirements are likely to introduce obstacles which may stand in the way of widespread acceptance of the system in supermarket environments. Firstly the battery will require replacement from time to time which, in a typical store having say 6000 modules, would be a time-consuming and costly exercise. Furthermore, whatever type of miniature antenna is used it is likely that areas of poor transmission/reception will be encountered and this would detract from the overall performance and acceptability of the system. The requirement for the installation of transmitter antenna throughout the store also means that this system does not totally eliminate store wiring. A system using r.f. transmission requires also, approval of the authorities controlling r.f. transmission and this creates a further inconvenience and possible delay at the outset.
Accordingly, it is an object of this invention to provide an improved data transmission system which obviates one ore more of the aforementioned problems of the known systems or such a system which at least provides a useful alternative.